The invention relates to chairs and chair bases and more particularly to a chair and chair base for reducing back strain in occupational situations where lateral movement from a seated position is an advantage.
Many occupational situations require lateral or side to side movement in a sitting position. Dealers and croupiers in casinos, postal sorters, office workers and receptionists etc. are often required to slide from side to side in the course of their work. In a healthy individual, this kind of repetitive motion may be a source of strain or injury. In a person with an existing back injury, this kind of motion may preclude them from working effectively, or at all. As the lateral motion is accomplished largely by the base of the chair (as opposed to the seat) there exists therefore, a need for a chair, or for a chair base adapted to receive a seat, which allows the user to move laterally, with minimum effort.
It is desirable that a chair or chair base be provided that alleviates the above problems.
According to a first aspect of the invention, there is provided a base for a seat or chair comprising
a chassis;
a landing provided on the chassis;
a carrier slideable in a xe2x80x9csidewaysxe2x80x9d direction along the landing, the carrier being adapted to support or capable of supporting, a seat or chair facing or able to face, an xe2x80x9cinxe2x80x9d direction which is at 90xc2x0 to said xe2x80x9csidewaysxe2x80x9d direction;
a carrier braking means having a friction material that is moveable towards and away from the landing, the carrier braking means being such that the carrier can only be freely slid along the landing when the braking means is released;
the braking means being releasable by the weight of an occupied seat or chair that serves to move the friction material away from contact with the landing and thus release the braking means, which is otherwise adapted to cause the friction material to remain in contact with the landing.
The carrier braking means may include a compressible member adapted to be compressed by the weight of the occupied seat or chair to move the friction material away from contact with the landing.
The chassis may be provided with means to facilitate it being moved in opposite xe2x80x9cinxe2x80x9d or xe2x80x9coutxe2x80x9d directions. Said means may include wheels that are retractable with respect to the chassis. In particular, said means may include lockable wheels.
The landing may be defined by spaced rails.
The carrier may be supported by wheels, which are positioned on said rails to permit movement of the carrier with respect to said rails.
The invention extends to a base, as described above, in a combination wherein the carrier supports a seat or chair facing, or able to face, an xe2x80x9cinxe2x80x9d direction which is at 90xc2x0 to said xe2x80x9csidewaysxe2x80x9d direction.
According to a second aspect of the invention, there is provided a base for a seat or chair, the base comprising
a support structure;
a carrier that is arranged on the support structure, a seat or chair being mountable on the carrier to be supported above the support structure;
a linear displacement mechanism to permit linear displacement of the carrier relative to the support structure; and
a brake mechanism that is arranged between the carrier and the support structure to inhibit linear displacement of the carrier relative to the support structure, the brake mechanism being biased into an operative condition when the seat or chair is not in use and being releasable when a threshold weight bears on the carrier, said threshold weight being based on a selected minimum weight of a person envisaged using the seat or chair.
A number of wheels may be mounted on the support structure to facilitate movement of the support structure relative to a substrate. The base may include a retracting mechanism that is operable on the wheels to retract the wheels. Further, the base may include a locking mechanism that is operable on the wheels to lock the wheels against rotational movement.
The support structure may include at least two spaced, substantially parallel, elongate members, the carrier being supported on the elongate members and being displaceable along the elongate members, the elongate members being of sufficient length to provide a desired extent of movement of the carrier.
The carrier may include at least two engaging formations that are slideably engaged with respective elongate members so that the carrier is slideable with respect to the elongate members. The elongate members may be circular cylindrical and the engaging formations may be in the form of collars that are slideably mounted on the respective elongate elements.
The carrier may include at least two wheel arrangements. Each wheel arrangement may include a weight bearing roller that is rotatably engaged with a respective elongate member so that the carrier can be wheeled back and forth along the elongate members.
Each elongate member may be shaped to define an operatively upper support surface on which the respective weight bearing rollers are supported.
Each wheel arrangement may include a guide roller that is engageable with a respective elongate member to guide movement of the carrier on the elongate members.
In a further embodiment, each elongate member may define a suspension track and each wheel arrangement may define a bogey that is positioned on a respective track, the carrier being suspended from the bogeys.
According to a third aspect of the invention, there, is provided a chair that includes a base as described in the second aspect of the invention.